The Regia Marina was established on 17 March 1861 following the proclamation of the formation of the Kingdom of Italy. Just as the Kingdom was a unification of various states in the Italian peninsula, so the Regia Marina was formed from the navies of those states, though the main constituents were the navies of the former kingdoms of Sardinia and Naples. The new Navy inherited a substantial number of ships, both sail- and steam-powered, and the long naval traditions of its constituents, especially those of Sardinia and Naples, but also suffered from some major handicaps.

Firstly, it suffered from a lack of uniformity and cohesion; the Regia Marina was a heterogeneous mix of equipment, standards and practice, and even saw hostility between the officers from the various former navies. These problems were compounded by the continuation of separate officer schools at Genoa and Naples, and were not fully addressed until the opening of a unified Naval Academy at Livorno in 1881.

Secondly, unification occurred during a period of rapid advances in naval technology and tactics, as typified by the launch of Gloire by France in 1858, and later by the appearance of, and battle between, USS Monitor and CSS Virginia in 1862. These innovations quickly made older warships obsolete. Italy did not possess the shipyards or infrastructure to build the modern ships required, but the then Minister for the Navy, Admiral Carlo di Persano, launched a substantial programme to purchase warships from foreign yards.

The Italian fleet, commanded by Admiral Persano, mustered 12 ironclad and 17 wooden-hulled ships, though only one, Affondatore, was of the most modern turret ship design. Despite a marked disadvantage in numbers and equipment, superior handling by the Austrians under Admiral Wilhelm von Tegetthoff resulted in a severe defeat for Italy, which lost two armoured ships and 640 men.

After the war, the Regia Marina passed through some difficult years as the naval budget was substantially reduced, thus impairing the fleet's efficiency and the pace of new construction; only in the 1870s, under Simone Pacoret de Saint Bon's ministry, did the situation begin to improve. In 1881, the battleship Caio Duilio was commissioned, followed in 1882 by the battleship Enrico Dandolo; at the time these were the most powerful warships in the world, and signalled the Italian fleet's renewed power. In 1896 the corvette Magenta completed a circumnavigation of the world. The following year the Regia Marina conducted experiments with Guglielmo Marconi in the use of radio communications. 1909 saw the first use of aircraft with the fleet. An Italian naval officer, Vittorio Cuniberti, was the first in 1903 to envision in a published article the all-big gun battleship design, which would be later come to be known as dreadnought.

In 1911 and 1912, the Regia Marina was involved in the Italo-Turkish War against forces of the Ottoman Empire. As the majority of the Ottoman fleet stayed behind the relative safety of the Dardanelles, the Italians dominated the Mediterranean during the conflict winning victories against Ottoman light units at the Prevenza and the Battle of Beirut. In the Red Sea the Italian forces were vastly superior to those of the Ottomans who only possessed a squadron of gunboats there. These were destroyed while attempting to withdraw into the Mediterranean at the Battle of Kunfuda Bay.

During the war, the Regia Marina spent its major efforts in the Adriatic Sea, fighting the Austro-Hungarian Navy. The resulting Adriatic Campaign of World War I consisted mainly of Austro-Hungarian coastal bombardments of Italy's Adriatic coast, and wider-ranging German/Hungarian submarine warfare into the Mediterranean. Allied forces mainly limited themselves to blockading the German/Hungarian navies in the Adriatic, which was successful in regards to surface units, but failed for the submarines, which found safe harbours and easy passage into and out of the area for the whole of the war. Considered a relatively minor part of the naval warfare of World War I, it nonetheless tied down significant forces.

For most of the war the Italian and Austro-Hungarian navies each kept a relatively passive watch over their adversaries. The Italian fleet lost the pre-dreadnought battleship Benedetto Brin at Brindisi (27 September 1915) and the dreadnought Leonardo da Vinci at Taranto (2 August 1916) due to a magazine explosion (although there were rumours of Austrian sabotage). In the last part of the war, the Regia Marina developed new weapons: the MAS boats, that sank the Austro-Hungarian battleship SMS Szent István in the Adriatic Sea on 10 June 1918; and an early type of human torpedo (Mignatta) entered the harbour of Pula and sank the Austro-HungarianflagshipSMS Viribus Unitis on 1 November 1918 shortly before the end of hostilities. The battleship SMS Tegetthoff (sister of the former two) was handed over to Italy as a war prize in 1919.

During the interwar years the Italian government set about modernizing the Regia Marina in a way that could enable it to reach dominance over the Mediterranean Sea. Italian naval construction was limited by the Washington Naval Conference. The 1922 treaty required a parity in naval forces between the Italian and French navies, with equality in total displacement in battleships and carriers. The treaty influenced the development of the Italian fleet over the years between the two world wars. Between the late twenties and early thirties a construction program began, focusing first on cruisers up to 10,000 tons, followed by the building of destroyers and submarines, and lastly the construction of the new Littorio-class battleships; plans were also put in place to modernize the Conte di Cavour-class and Andrea Doria-class battleships. Much of these new naval units were responses to French naval constructions, as the Marine nationale was seen until the mid 1930s as the most likely enemy in a hypotetical conflict.

The Regia Marina choose to build fast ships armed with longer ranged guns to give the Italian vessels the ability to minimize close contact with vessels of the Royal Navy, whose crews were more experienced and efficient. In theory this would allow them to engage or break off at their own choosing, and would allow them to hit the enemy when he could not yet hit back. New guns were developed with longer ranges than their British counterparts of similar caliber. Speed was emphasized in their new construction. Subsequently newer Italian cruisers such as the Giovanni dalle Bande Nere were built with a newly designed and relatively thin armour. The armor of these vessels was 24 mm, as compared to 102 mm on their contemporarys, the British Leander class. This would have a decisive role in a number of naval battles, including the Battle of Cape Spada.

Caio Duilio after refitting.

The modernization work on the four Great War era battleships turned into a significant reconstruction project, with only 40% of the original structures being left. The ship's guns were upgraded in main armament, going from 13 guns of 305mm diameter, to 10 guns of 320mm diameter. The middle turret and the vessel's central tower were eliminated. To increase speed the coal-fired boilers were replaced with modern oil-fired boilers and ten meters were added to the ship's length to improve the coefficient of fineness. Though the ships were improved, they still were not an equal match for the Queen Elizabeth-class battleships and the Renown-class battlecruisers, both of which carried larger guns and heavier armour.

Regarding technological development, however, the Italian leadership took a very conservative view. Little to no attention was devoted to incorporating new technologies. Though scientific research on tracking devices, such as radar or sonar, were being conducted in Italian universities and military laboratories by men such as Ugo Tiberio and Guglielmo Marconi, the developments were not brought in to improve the effectiveness of the Italian vessels. This was mainly due to the influence of Admiral Cavagnari, whom Mussolini appointed as Chief of Staff of the Navy in 1933, and whom he later promoted to Secretary of the Navy. Likewise technological advancement in radio range finders and gunnery control devices for night combat were not incorporated. Regarding such devices, Cavagnari emphasized "not wanting traps in your way". Writing to Admiral Iachino, he wrote "..procedere con estrema cautela nell'accettare brillanti novità tecniche che non siano ancora collaudate da una esperienza pratica sufficientemente lunga..", which can be tranlsated to "... proceed with extreme caution regarding brilliant technical innovations that have not yet been tested or with which there is no practical experience." Thus, the Italian navy entered the Second World War with a marked technical inferiority to the British Navy. German General Albert Kesselring, overall commander of Axis forces in the Mediterranean, observed that the Italian navy was "a good weather" force, unable to operate effectively at night or in heavy seas.

Two training ships were built during this period, in addition to the effort to modernize and re-equip the combat vessels of the navy. These were square rigged school ships the Regia Marina ordered in 1925. The sailing ships followed a design by Lieutenant Colonel Francesco Rotundi of the Italian Navy Engineering Corps, reminiscent of ships of the line from the Napoleonic era. The first of these two ships, Cristoforo Colombo, was put into service in 1928 and was used by the Italian Navy for training until 1943. After World War II, this ship was handed over to the Soviet Union as part of war reparations and was shortly afterwards decommissioned. The second ship of the design was Amerigo Vespucci. The ship was built in 1930 at the (formerly Royal) Naval Shipyard of Castellammare di Stabia (Naples). She was launched on 22 February 1931, and was put into service in July of that year. She is still being used to this day.

At the time of the Italian intervention in the Spanish Civil War, the Regia Marina sent naval units in support of the Italian Corps of Volunteer Troops (Corpo Truppe Volontarie). Approximately 58 Italian submarines took part in operations against Republican naval forces of Spain. These submarines were organized in a Submarine Legion and complemented German U-boat operations as part of Operation Ursula. At least two Republican freighters, one Soviet and another Panamanian were either sunk or forced to run aground by Italian destroyers near the Strait of Sicily.[1] Two light cruisers took part in the shelling of Barcelona and Valencia in 1937, resulting in the deaths of more than 30 civilians.[2]

In 1939, the Regia Marina supported the invasion of Albania. All ground forces involved in the invasion had to cross the Adriatic Sea from mainland Italy and the crossings were accomplished without incident.

Before the declaration of war, Italian ground and air forces prepared to strike at the beaten French forces across the border with France. By contrast, the Regia Marina prepared to secure the lines of communications between Italy, Libya, and the East African colonies. The Italian High Command (Comando Supremo) did not approve of the plan devised by the Italian Naval Headquarters (Supermarina) to occupy a weakly defended Malta.[4] This proved a crucial mistake. At the time, the British Army and Air Force did not think Malta could be defended due to the close proximity of Italian air bases in Italy, Sicily and Libya. Due to this, hardly any effort was made to bolster Malta's defences until it was too late. Thus, at the outset of the war there were only 42 antiaircraft guns on all of the island, and twelve Gloster Sea Gladiators, half sitting in crates at the wharf.[5]

Entering the war, the Regia Marina was operating under a number of limitations. Though significant assets were available to challenge the Royal Navy for control of the Mediterranean, there had been a lack of emphasis on the incorporation of technological advances such as radar and sonar. This meant that in night engagements or foul weather, the Italian ships were unable to detect the approach of their British adversaries. When engaged, they lacked the ability to range their guns if they were unable to visually locate their targets.

The Regia Marina had six battleships with which to contend for control of the Mediterranean, the four most modern of which were being re-fit at the time of the outbreak of the war. In addition to the six capital ships, the Italians had 19 cruisers, 59 destroyers, 67 torpedo boats, and 116 submarines. Though the Regia Marina had a number of new cruisers built to be faster ships with good range in their gunnery, they were lightly built and had inadequate defensive armoring. Numerically the Italian fleet was formidable, but there were a large number of older vessels, and the service suffered in general from insufficient time at sea for crew training.

Italy's lack of raw materials meant that they would have great difficulty building new ships over the course of the war. Thus, the assets they did have were handled with caution by the Italian Naval Headquarters. Whereas Allied commanders at sea had a fair degree of autonomy and discretion to fight their vessels as circumstance allowed, the Italian commanders were required to confer with the headquarters before committing their forces in an engagement that might result in their loss. This led to delays in arriving at decisions and actions being avoided, even when the Italian forces had a clear advantage. An example occurred during "Operation Hats", where the Regia Marina had superior forces but failed to commit them to take advantage of the opportunity.[6]

A further key disadvantage in the convoy support and interception battles that dominated the Battle of the Mediterranean was the intelligence advantage the British held in their Ultra intercept system. Ultra decrypts provided the Royal Navy with key information on convoy routes, times of departure, routing, time of arrival and make up of the convoy.

The warships of the Regia Marina had a general reputation as being well-designed. Italian small attack craft lived up to expectations and were responsible for many successful actions in the Mediterranean. But some Italian cruiser classes were rather deficient in armour. Though Italian warships lacked radar, this was partly offset in fair weather by Italian optical rangefinder and fire-control systems.[7]

In addition the Italian Navy lacked a fleet air arm. The high command had reasoned that since the Italian navy would be operating solely in the Mediterranean, their vessels would never be far from an airfield, thus the time and resources needed to develop a naval air arm could be directed elsewhere. This proved problematic on a number of occasions. Though the Italians did have the aircraft carriers Aquila and Sparviero under construction at the start of the war, neither one was ever completed.[3] Lastly, the lack of natural oil reserves and subsequent shortage of oil precluded extensive fleet operations.[4]

The Regia Marina and the Royal Navy engaged in a two and a half year struggle for control of the Mediterranean. The Regia Marina‍ '​s primary goal was to support the Axis forces in North Africa while obstructing the supply route to Alexandria and cutting off supplies to Malta. The Royal Navy's major effort was to maintain supply to the military forces and people of Malta, and secondarily to interdict convoy shipments to North Africa.[8][N 1] The first major action occurred on 11 November 1940 when the British aircraft carrier HMS Illustrious launched two waves of Swordfish torpedo-bombers in a surprise raid against the Italian Fleet moored at the naval base of Taranto. The raid came in undetected, and three battleships were sunk. Another major defeat was inflicted on the Regia Marina at Cape Matapan, where the British Royal Navy and the Royal Australian Navy intercepted and destroyed three heavy cruisers (Zara, Pola and Fiume; all of the same class) and two Oriani-class destroyers in a night ambush, with the loss of over 2300 seamen. The Allies had Ultra intercepts, which uncovered the Italian movements, and radar, which enabled them to locate the ships and range their weapons at distance and at night. The better air reconnaissance skills of the British Royal Navy's Fleet Air Arm and their close collaboration with surface units were other major causes of the Italian debacle.

On 19 December 1941, the battleships HMS Queen Elizabeth and HMS Valiant were sunk in shallow water by limpet mines planted by Italian manned torpedoes, knocking both out of the conflict for almost two years. This action, coming on the heels of the loss of the Prince of Wales and Repulse in the South China Sea, significantly weakened the surface strength of the Royal Navy, making it difficult for them to challenge control of the eastern Mediterranean.[N 2]

On the night of 19 December, Force K, comprising three cruisers and four destroyers based at Malta, ran into an Italian minefield off Tripoli. Three cruisers struck mines, with the cruiserHMS Neptune lost, along with the destroyerHMS Kandahar. In addition, another destroyer was seriously damaged. All told 800 seamen were lost, and Force K, which had been effectively interdicting Axis convoys, was put out of action.

This series of successes allowed the Regia Marina to achieve naval supremacy in the central Mediterranean. Coupled with an intensive bombing campaign against Malta, the Axis supply routes from southern Europe to North Africa were almost untouched by the British Royal Navy or its allies for the next several months.

The Italian fleet went on the offensive, blocking or mauling three large Allied convoys bound for Malta. This led to a number of naval engagements, including the Second Battle of Sirte in March 1942, Operations Harpoon and Vigorous, (known as the "Battle of Mid-June"), and Operation Pedestal (the "Battle of Mid-August"). All of these engagements were favourable to the Axis. Despite this activity, the only real success of the Italian Fleet was the aerial and surface attacks on the Harpoon convoy. These attacks sank several Allied warships and damaged others. Only two transports of the original six in the convoy reached Malta. This was an undisputed squadron-sized victory for Italian surface forces in World War II.[N 3]

Despite the heavy losses suffered by the merchantmen and escorting forces of convoy Pedestal, the oil and supplies brought through allowed the near starving island of Malta to continue. With Allied landings in North Africa, Operation Torch, in November, the fortunes of war turned against the Italians. Their sea convoys were harassed day after day by the aerial and naval supremacy of the Allies. The maritime lane between Sicily and Tunisia became known as the "route of death". After years of back and forth, the Axis forces were forced to surrender in Tunisia, bringing the campaign for North Africa to a close.

The Regia Marina performed well and bravely in its North African convoy duties, but remained at a technical disadvantage. The Italian ships relied on a speed advantage, but could easily be damaged by shell or torpedo, due to their relatively thin armour. The fatal and final blow to the Italian Navy was a shortage of fuel, which forced its main units to remain at anchor for most of the last year of the Italian alliance with Germany.[11]

On 10 June 1941, the British launched Operation Chronometer and a battalion from the British Indian army was landed at Assab, the last Italian-held harbour on the Red Sea.[13] By 11 June, Assab had fallen. On 13 June, two days after the fall, the Indian trawler Parvati became the last naval casualty of the East African Campaign when it struck a moored mine near Assab.[14]

After Italy quit the war, most of the Italian vessels on the Black Sea were transferred to Nazi Germany's Kriegsmarine. By August 1944, they were ultimately captured by Soviet forces when Constanca was captured. The six submarines were transferred to the Royal Romanian Navy.

The Regia Marina operated a squadron of four MAS boats on Lake Ladoga during the Continuation War (1941–1944). As part of Naval Detachment K, German, Italian, and Finnish vessels operated against Soviet gunboats, escorts and supply vessels during the Siege of Leningrad between 21 June and 21 October 1942. The Italian vessels were ultimately turned over to Finland.

The Regia Marina had a naval base in the concession territory of Tiensin in China. The primary Italian vessels based in China were the mine-layer Lepanto and the gunboat Carlotto. During World War II, Italian supply ships, auxiliary cruisers and submarines operated throughout the waters of the Far East, often in disguise.[citation needed] The Italians also utilized Japanese-controlled port facilities such as Shanghai, China, and Kobe, Japan.

Twelve additional R-classblockade running transport submarines were specifically designed for trade with the Far East, but only two of these vessels were completed before Italy quit the war. Both of these submarines were destroyed by Allied action almost as soon as they were launched.

In 1943, Italian dictator Benito Mussolini was deposed and the new Italian government agreed to an armistice with the Allies. Under the terms of this armistice, the Regia Marina had to sail its ships to an Allied port. Most sailed to Malta, but a flotilla from La Spezia headed towards Sardinia. This was intercepted and attacked by German aircraft and the battleship Roma was sunk by two hits from Fritz X guided glide-bombs. Among the 1600 sailors killed on board Roma was the Italian Naval Commander-in-Chief, Admiral Carlo Bergamini.[15]

As vessels became available to the new Italian government, the Italian Co-Belligerent Navy was formed to fight on the side of the Allies. Other ships were captured in port by the Germans or scuttled by their crews. Few Regia Marina crews chose to fight for Mussolini's new fascist regime in northern Italy, the Italian Social Republic (Repubblica Sociale Italiana, RSI). Mussolini's pro-German National Republican Navy (Marina Nazionale Repubblicana) hardly reached a twentieth the size attained by the co-belligerent Italian fleet.[16] In the Far East, the Japanese occupied the Italian concession territory of Tiensin.

There was little use for the surrendered Italian battleships and there was doubt about the loyalties of the crews, so these ships were interned in Egypt. In June 1944, the less powerful battleships (Andrea Doria, Caio Duilio and Giulio Cesare) were allowed to return to Augusta harbour in Sicily for training. The others, Vittorio Veneto and Italia (ex-Littorio), remained at Ismaïlia in the Suez Canal until 1947. After the war, Giulio Cesare was passed to the Soviet Union.

In the Co-belligerency period, until "VE" (Victory in Europe) Day, Italian light cruisers participated in the naval war in the Atlantic Ocean with patrols against German raiders. Smaller naval units (mainly submarines and torpedo boats) served in the Mediterranean Sea. In the last days of war, the issue of whether Italian battleships and cruisers should participate in the Pacific War was debated by the Allied leaders.

There were also Italian naval units in the Far East in 1943 when the new Italian government agreed to an armistice with the Allies. The reactions of their crews varied greatly. In general, surface units, mainly supply ships and auxiliary cruisers, either surrendered at Allied ports (Eritrea at Colombo, Ceylon) or, if in Japanese controlled ports, they were scuttled by their own crew (Conte Verde, Lepanto, and Carlotto at Shanghai). Ramb II was taken over by the Japanese in Kobe and renamed Calitea II. Four Italian submarines were in the Far East at the time of the armistice, transporting rare goods to Japan and Singapore: Ammiraglio Cagni, Comandante Cappellini (Aquilla III), Reginaldo Giuliani, and Luigi Torelli. The crew of Ammiraglio Cagni heard of the armistice and surrendered to the Royal Navy off Durban, South Africa. Comandante Cappellini, Reginaldo Giuliani, and Luigi Torelli and their crews were temporarily interned by the Japanese. The boats passed to German U-boat command and, with mixed German and Italian crews, they continued to fight against the Allies. The German navy assigned new officers to the three submarines. The three were renamed UIT-23, UIT-24 and UIT-25 and took part in German war operations in the Pacific. Reginaldo Giuliani was sunk by the British submarine HMS Tally-Ho in February 1944. In May 1945, the other two vessels were taken over by the Japanese Imperial Navy when Germany surrendered. About twenty Italian sailors continued to fight with the Japanese. Luigi Torelli remained active until 30 August 1945, when, in Japanese waters, this last Fascist Italian submarine shot down a North American B-25 Mitchell bomber of the United States Army Air Forces.[17]

After the end of hostilities, the Regia Marina started a long and complex rebuilding process. At the beginning of the war, the Regia Marina was the fourth largest navy in the world with a mix of modernised and new battleships. The important combat contributions of the Italian naval forces after the signing of the armistice with the Allies on 8 September 1943 and the subsequent cooperation agreement on 23 September 1943 left the Regia Marina in a poor condition. Much of its infrastructure and bases were unusable and its ports mined and blocked by sunken ships. However, a large number of its naval units had survived the war, albeit in a low efficiency state. This was due to the conflict and the age of many vessels.

The vessels that remained were:

2 incomplete and damaged aircraft carriers

5 battleships

9 cruisers

11 destroyers

22 frigates

19 corvettes

44 fast coastal patrol units

50 minesweepers

16 amphibious operations vessels

2 school ships

1 support ship and plane transport

various submarine units

On 2 June 1946, the Italian monarchy was abolished by a popular referendum. The Kingdom of Italy (Regno d'Italia) ended and was replaced by the Italian Republic (Repubblica Italiana). The Regia Marina became the Navy of the Italian Republic (Marina Militare).

On 10 February 1947, a Peace Treaty was signed in Paris between the Italian Republic and the victorious powers of World War II. The treaty was onerous for the Italian Navy. Apart from territorial and material losses, the following restrictions were imposed:

A ban on owning, building or experimenting with atomic weapons, self-propulsion projectiles or related launchers

The total displacement, battleships excluded, of the future navy was not allowed to be greater than 67,500 tons, while the staff was capped at 25,000 men.

The treaty also ordered Italy to put the following ships at the disposals of the victorious nations United States, Soviet Union, Great Britain, France, Greece, Yugoslavia, and Albania as war compensation:

^The British Official History states "All the major operations of the Royal Navy in the Mediterranean in 1942 prior to the Anglo-American landing in November were concerned with taking convoys into Malta."[8]

^"Consequently, the Alexandria Fleet remained for many months without any battleships, and it was forced to abandon any further open activity. In fact, Admiral Cunningham wrote that his Fleet now should have to leave it to the Royal Air Force to try if they could dispute the control of the Central Mediterranean with the enemy's fleet.(...) In fact, it opened a period of clear Italian naval supremacy in the east-central Mediterranean".[9]

^"Clearly this was an Axis victory and a tactical victory for the Italian Navy. Part of the convoy did get through to Malta, but the British suffered far heavier losses than did the Italians and Mussolini would later personally present medals to Da Zara and some of his men for their efforts. It would be the only squadron-sized surface naval victory of the war for Italy."[10]